CPP trailing arm crossmember??

[tk-mpl]

I am trying to put in a rear trailing arm crossmember in my 68 C10. It is a dropped CPP one. I have found out that the previous owner cut a long box frame into a short box and then moved and welded in the stock crossmember. Without thinking I did not mark the position of the stock one before I cut it out. Is there anything that I could reference from the front of the frame and measure up to put the crossmember in the right place.
Anybody got pictures and measurements.
Thanx.